CVE-2021-43080 in FortiOS
Summary
by MITRE • 09/06/2022
An improper neutralization of input during web page generation vulnerability [CWE-79] in FortiOS version 7.2.0, version 6.4.0 through 6.4.9, version 7.0.0 through 7.0.5 may allow an authenticated attacker to perform a stored cross site scripting (XSS) attack through the URI parameter via the Threat Feed IP address section of the Security Fabric External connectors.
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Analysis
by VulDB Data Team • 10/14/2022
The vulnerability identified as CVE-2021-43080 represents a critical security flaw in Fortinet's FortiOS platform that falls under the Common Weakness Enumeration category 79, which specifically addresses improper neutralization of input during web page generation. This weakness creates an environment where malicious actors can exploit the system's failure to properly sanitize user-supplied data before incorporating it into web page content. The vulnerability affects multiple versions of FortiOS including the 7.2.0 release, versions 6.4.0 through 6.4.9, and versions 7.0.0 through 7.0.5, indicating a widespread impact across the FortiOS product line.
The technical flaw manifests within the Threat Feed IP address section of the Security Fabric External connectors module, where the system fails to adequately sanitize the URI parameter input. This allows an authenticated attacker with sufficient privileges to inject malicious scripts that will be executed when other users view the affected web pages. The vulnerability specifically targets the web page generation process where user-provided input is directly incorporated into HTML output without proper sanitization or encoding mechanisms. The stored nature of this cross-site scripting attack means that the malicious payload is permanently stored on the server and will be executed each time the affected page is accessed by any user.
The operational impact of this vulnerability is significant as it enables authenticated attackers to execute arbitrary code within the context of the victim's browser, potentially leading to session hijacking, data theft, or further system compromise. Attackers can leverage this weakness to manipulate the security fabric configuration, access sensitive information, or redirect users to malicious websites. The fact that this affects the Security Fabric External connectors module means that compromised systems could impact the overall security posture of networks relying on Fortinet's security infrastructure. This vulnerability directly maps to ATT&CK technique T1059.005 for command and scripting interpreter, and T1566.001 for credential access through social engineering, as attackers could use the XSS payload to capture user credentials or escalate privileges.
Organizations affected by this vulnerability should immediately implement mitigations including applying the latest security patches released by Fortinet, implementing network segmentation to limit access to the affected modules, and monitoring for suspicious activity in the Security Fabric External connectors section. Additional protective measures should include enforcing strict input validation policies, implementing content security policies, and conducting regular security assessments of web applications to identify similar input sanitization flaws. The vulnerability highlights the critical importance of proper input validation and output encoding in web applications, as outlined in OWASP Top Ten and the CWE guidelines for preventing cross-site scripting attacks. Security teams should also consider implementing web application firewalls and intrusion detection systems to monitor for exploitation attempts targeting this specific weakness.